Gang saws for cutting long lengths of board, logs or tree trunks into a plurality of shorter lengths are very old. The concept of arranging the saws in staggered order to prevent binding which often happens when the saws are aligned, is like-wise well understood. In general, the saws used in prior tree slashers have been circular saws which are expensive. When circular saws are damaged to the extent that replacement is necessary, the slasher must be shut down for a relatively long time to make the change. Chain saws as substitutes for circular saws have come into limited use in some of the smaller machines. Those machines, however, that are large enough to slash whole tree trunks simultaneously into multiple lengths still rely primarily on the circular saws. Likewise, while log slashers have been mounted on wheels to facilitate transport of the slasher to the logging site, the general practice is to establish the slasher at a relatively permanent location and bring the logs or tree trunks to the machine for cutting.
The following U.S. patents are illustrative of the prior and present state of the art: Allen, No. 95,406; Stearns, No. 238,815; Williams, No. 247,791; Murray, No. 288,723; Gately, No. 487,947; Perron, No. 832,273; Cleveland, No. 1,082,405; Kramer, 1,122,402; Sturm, 1,332,477; Richardson, No. 1,969,425; Gerdine, No. 2,635,659; Tanguay, No. 3,500,882; Dobbs, No. 3,604,481; Neumann, No. 3,623,517; and Heimeri, No. 3,771,395.
It will be noted in the foregoing mentioned prior patents that extensive work has been done in the art of tree slashing and the somewhat related field of lumber trimming. Circular and chain saws have been used; the sawing units have been used mounted on wheels for transportation to desired sawing locations; when gangs of saws are used, it would appear that circular saws are preferred; when a number of logs are to be sawed simultaneously, a chain saw having greater length than the workable radius of the average circular saw is often used.
Individual saws of gang saw assemblies have been made moveable to be withdrawn from cutting position when no cut at that location is wanted.
In summary, it would appear in the tree slasher art that the prior patentees have tried many combinations of saws, various drives for saws, mobile and permanently located slashers but in spite of the wealth of knowledge in this field, no tree slasher has emerged which has found general acceptance by the large corporations which are continuously engaged year after year in the felling of trees and the subsequent cutting of the tree trunks into appropriate lengths for processing into paper pulp, into cut lumber or whatever.